Automatic safety valve

ABSTRACT

A self-contained, automatic valve assembly designed to be anchored at a subsurface location within a well casing which extends into a subterranean formation employed to store pressurized gas. The valve is supported by a retrievable packer which anchors the valve within the casing and forms a seal to force the gas to flow through the valve. Operation of the valve is governed by a bellows control which moves a valve stem to closed position to terminate flow through the valve in response to a drop in casing pressure.

United States Patent Garrett May 20, 1975 [54] AUTOMATIC SAFETY VALVE giggly; gofiison ,7 0 1801'] 1 lnvemofi Henry Garrett, Longvlew, 3.593.784 7/1971 Brown 166/!25 [73] Assignee: Macco Oil Tool Co., Inc, Houston,

Tex. Primary Examiner-James A. Leppink [22] Filed Nov 28 1973 Attorney, Agent, or Firm-Torres & Berryhill [21] Appl. No.: 419,513 ABSTRACT 62 D. i :22??? Q 2 P, N A self-contained, automatic valve assembly designed 1 3 une to be anchored at a subsurface location within a well casing which extends into a subterranean formation employed to store pressurized gas. The valve is supfi 166/133 /a i ported by a retrievable packer which anchors the 224 A 125 valve within the casing and forms a seal to force the 1 1e 0 earc 1 s 6 gas to flow through the valve. Operation of the valve is governed by a bellows control which moves a valve References Cited stem to closed position to terminate flow through the valve in response to a drop in casing pressure.

13 Claims, 9 Drawing Figures PATENTED HAYZUIQYS SHEET 3 OF 3 AUTOMATIC SAFETY VALVE CROSS REFERENCE TO RELATED APPLICATIONS This application is a divisional of U.S. patent application Ser. No. l53,6l7, filed June 16, 1971 entitled AU- TOMATIC SAFETY VALVE now U.S. Pat. No. 3,802,504.

BACKGROUND OF THE INVENTION l..Field of the Invention The present invention relates to automatic safety equipment designed to regulate the flow of fluids through a flow conduit. As used herein, the term fluid" is intended to encompass both liquids and gases. In the preferred application, the present invention relates to a self-contained, automatically closing safety valve designed to be anchored in an in-place well casing extending into a gas storage reservoir to prevent the escape of stored gas through the casing following failure of or damage to the casing or the wellhead structure.

During the slack gas usage months, gas produced in one geographical area is often piped to depleted gas formations located in the colder climates where it is stored for use in the colder months. Well structures extending into the storage formations normally include a single string of casing through which the gas is injected into the formation during the storage phase and through which gas is extracted during the usage phase. Safety equipment is required to be employed within the casing to automatically terminate gas flow in the event the wellhead structure or casing should fail.

In order to prevent automatic safety equipment from being damaged and to position the equipment in its most useful location, it is desirable that the equipment be positioned as far as possible below the surface of the well. Such placement protects the equipment from surface impact and minimizes the amount of casing exposed to leakage. Because the gas moves in one direction when it is being injected into the subsurface formation and in another direction when it is being extracted from the formation, subsurface valves employed in the equipment must be capable of permitting such flow while maintaining their ability to close automatically in the event of uncontrolled flow.

2. Description of the Prior Art Subsurface safety equipment customarily employed in well conduits includes valving mechanisms which are included in the well conduit as an integral part of the well conduit itself. Such mechanisms are lowered into the desired subsurface location as a part of the conduit when the well is completed. Retrieval of these integral mechanisms for repair or replacement requires that the well conduit be withdrawn from the well. Another prior art system which eliminates the need for extracting the entire well conduit for repair or replacement of the safety equipment employs a specially designed landing nipple which is included as a part of the well conduit when the conduit is lowered into the well. A retrievable valving and control assembly may then be lowered through the conduit to latch into special recesses provided in the nipple.

In many of the older storage formations, the casing is cemented in place and cannot be retrieved from the well. Other circumstances also make it impossible or undesirable to remove the casing from the well bore to equip it with safety equipment. Conventional safety valves are not designed to be employed in such unequipped casing.

SUMMARY OF THE INVENTION The valve of the present invention is designed to be run into a well casing and anchored in place with a retrievable well packer. The packer may include dogs to engage the collar recess between tubing sections or may have slips with friction teeth to anchor along the smooth casing wall.

The valve design includes a tubular valve housing through which a substantially tubular valve stem moves linearly to open or close the valve flow passage. In one axial position of the stem, slots cut through tubular walls both in the stem and in the housing align radially to open the flow passage. The passage is closed by moving a sealing surface on the stern into engagement with a seating surface formed on the housing. Movement of the stern through the housing is governed by a pressure responsive, bellows equipped control means.

The bellows chamber of the control means is enclosed and is completely filled with an incompressible fluid. A two-way bellows protection mechanism mounted within the fluid moves between axially separated seating surfaces to protect the bellows from damage due to exposure to high pressures. Movement of fluid in the bellows is slowed by a small orifice opening to provide a damping effect which protects the components of the control means from damage caused by sudden pressure changes.

Closing of the safety valve is effected by sudden release of a compressed spring to provide a snap closing action which ensures complete seating of the stem against the housing seat. Spring forces are also employed to both provide a closing force in the event' of damage to the bellows section and to assist in resetting the snap action mechanism when the valve is reopened. A pressure bypass passage is opened across the closed valve by a setting tool for equalizing any pressure differential which may exist to facilitate reopening of the valve.

The packer is preferably of the type which may be wireline set and retrieved to minimize operating expenses and to reduce losses in production time. A relatively large, unimpeded flow passage is opened through the valve to increase the rate of fluid flow through the assembly. The sealing and. seating surfaces employed in the closure means of the valve are withdrawn from the flow path of the fluids'when the valve is open to prevent abrasive cutting and wear. An operator extending axially through the center of the valve stern in designed to be pushed down by the setting mechanism to depress a sealing piston which opens the bypass passage. A seal piston extends between the operator and the valve stem to protect the internal components of the control mechanism from damage caused by the accumulation of sediment or debris.

The foregoing and other features and advantages of the present invention will be more fully understood from the following specification, claims and the related drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical elevation, partially in section illustrating the automatic safety valve of the present invention anchored by a retrievable packer at a subsurface location in a well casing;

FIG. 2 is a partial, vertical elevation, in quartersection, illustrating the valve and control portions of the present invention with the valve in a stabilized, closed position;

FIG. 3 is a view similar to FIG. 2 illustrating the valve and control components immediately following movement of the closure components of the valve from open to closed position prior to stabilized closure;

FIG. 4 is a view similar to FIG. 3 illustrating the valve in a stabilized, fully opened position;

FIG. 5 is a view similar to FIG. 2 illustrating a surface operated latching device attached to an operator in the valve to hold the valve in closed position as an emergency measure;

FIG. 6 is a view similar to FIG. 2 illustrating a surface operated setting mechanism telescoped over the end of the operator employed to open a pressure bypass to equalize pressure across the closed valve so that the assembly may be released and moved through the well casing;

FIG. 7 is a horizontal cross-sectional view taken along the line 77 of FIG. 4;

FIG. 8 is a horizontal cross-sectional view taken along the line 8-8 in FIG. 3; and

FIG. 9 is a horizontal cross-section taken along the line 99 of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT The automatic safety valve assembly of the present invention is indicated generally at 10in FIG. 1. Components included with the asembly 10 include a packer P, a valving section V and a control section C. The assembly 10 is illustrated anchored in position at a subsurface location within a tubular well casing W. The packer P is of conventional construction and includes an elastomeric seal S and radially expansible and retractable anchoring devices A. As illustrated in FIG. 1, the anchoring elements A are dogs which have been expanded into an annular collar recess formed between upper and lowercasing sections Wu and Wb, respectively, joined together by a collar Wc. As is customary, setting of the packer causes the anchoring dogs A to extend radially and simultaneously causes the elastomeric seal S to expand radially outwardly. Expansion of the packer seal forms a pressuretight seal between the body of the packer and the surrounding walls of the casing W. Once set, the packer anchors the assembly in place and forces all well fluids in the casing W to flow through the valve section V.

The packer P may be similar to that described in US. patent application, Ser. No. 857,047, filed Sept. 11, 1969, entitled ANCHOR ASSEMBLY FOR WELL TOOLS SUCH AS PACKERS AND THE LIKE, now U.S. Pat. No. 3,593,784 issued July 20, 1971, or similar to that described in U.S. patent application, Ser. No. 272, filed Jan. 2, 1970, entitled TOOL STRING AS- SEMBLY FOR USE IN WELLS now U.S. Pat. No. 3,633,670, issued Jan. I l, 1972. Any packer employed to anchor the valve mechanism V within the casing W is preferably retrievable and includes a large central opening to permit relatively unimpeded flow of fluid through the assembly. Where collar recesses are not available, or where otherwise desired, and anchoring dogs A may be replaced by conventional slips having friction creating teeth formed along their external surfaces.

Details in the construction of the valve and control portions of the present invention are illustrated in FIG. 2 which shows the valve components as they appear in a stabilized, closed position. The valve section V includes a tubular valve housing 11 which is threadedly engaged to the base of an adapter section 12. The adapter section 12 is in turn connected to the body of the packer P to support the depending valve section V and control section C. A tubular control housing 13 is threadedly secured to the base of valve housing 11 and is employed to support and protect pressure responsive bellows and spring components contained within the control C.

A linearly movable valve stem 14 is carried within the valve housing 11 and is mounted to be moved axially within the tubular valve housing 11 under the influence of the bellows and spring control components contained within the control housing 13. The valve stem 14 is of composite construction and includes a tubular sealing head 15 threadedly engaged to a detent holder 16 which in turn is threadedly secured at its lower end to a recocking sleeve 17. The outer external surface of the head 15 is equipped with a circumferentially extending seal mount which supports an annular seal 18 ofa suitable elastomeric material. The seal 18 encircles the head 15 and, when the valve stem 14 is in its uppermost axial position as illustrated in FIG. 2, the seal 18 is designed to engage and seal against a seating surface 19a formed in an annular seat ring 19 to prevent flow through the valve. The ring 19 is removably mounted between the base of adapter 12 and an inwardly developed shoulder 20 formed along the internal wall of the valve housing 11. When the seating surface 19a becomes worn, the ring may be removed and replaced by simply unthreading the valve housing 11 from the adapter 12.

When the valve stem 14 is in its lowermost axial position as illustrated in FIG. 4 of the drawings, circumferentially developed slots 21 formed through the walls of valve housing 11 communicate with similar slots 22 formed through the tubular walls of the stem head 15 to provide a flow passage through the valve V. The flow passage permits liquids or gases in the casing W above and below the set packer seal S to flow in either direction through the valve V and packer P.

The stem head 15 supports an axially movable central operator 23. The operator includes an upper segment 23a having a tapered head 23a, a downwardly facing annular shoulder 23b formed below the head 23a and a second downwardly facing shoulder 230 formed along the shank of the upper segment. A lower body segment 23d threadedly engaged to the upper seg ment 23a is equipped with an upwardly facing shoulder 23e formed at its base. An annular debris seal 24 encircles the shank of control 23 to prevent sand and silt and other debris from falling down between the operator and the surrounding stem head. A coil spring 25 mounted between the seal 24 and an annually developed shoulder in the stem head 15 biases the seal 24 upwardly into engagement with the shoulder 23b. An annular O-ring seal 26 of a suitable elastomeric material extends about the seal 24 to provide a sliding, sealing engagement with the internal walls ofthe stem head 15. A removable snap ring 27 set within a receiving groove formed in the wall of stem head provides an upper axial restraint to retain the seal 24 within the receiving bore formed by the surrounding walls of the stem head 15.

An axially movable valving piston 28 having upper and lower annular O-ring seals 28a and 28b carried along its outer circumferential surface is mounted between the operator 23 and the stem head 15 to control opening and closing of a pressure bypass passage. A helical spring 29 positioned between the piston 28 and the upper surface of the detent holder 16 functions to retain the upper end of the piston in engagement with the shoulder 230 formed on the operator 23. Sliding sealing engagement between the operator 23 and holder 16 is provided by an O-ring operator seal 23]".

Upper axial movement of the piston 28 is limited by an inwardly developed shoulder 31 extending from the inner wall of the stem head 15. Axially developed bores 28c extend through the upper end of the piston 28 to provide a pressure relief passage which when opened relatively large pressure differentials across the closed valve to be slowly equalized before the valve is reopened. As will be seen, when the piston 28 is in its uppermost axial position in engagement with the shoulder 31, bypass flow passages 30 extending radially through the walls of the stem head 15 are bridged by the O-rings 28a and 28b which seal the passages 30 from the area between the operator 23 and the internal walls of the stem head 15. With the valve stem 14 and piston 28 at their uppermost positions, the main seal 18, operator seal 23f and bypass O-ring seals 28a and 28b prevent any flow through the valve assembly.

If it becomes necessary to move the valve, any pressure differential existing across the closed valve is equalized by depressing the piston 28 to open the passages 30. Opening of the valve by mechanical means may be difficult or impossible where a relatively high pressure differential exists across the valve. As best illu'strated in FIG. 6, pressure equilization across the closed valve is effected with the use of a suitable surface operated setting mechanism F which engages the operator 23 and moves it downwardly through the closed valve stem 14. In this position, the operator 23 forces the piston 28 downwardly against the resisting force of spring 29 'to open the flow passages 30. The low pressure area existing within the stem head 15 is thereby communicated through openings F-l formed in the base of the setting mechanism F, through the annular area between the operator 23 and the surrounding walls of the stem head 15 and through the radial flow passage openings 30 to the area within the well casing, externally of the valve V and below the seal S.

A triggering mechanism 33 surrounds the lower operator segment 23d and is employed to control the radial movement of a plurality of metal spherical detent balls 34. The balls are positioned for radial movement in a bore 16a formed in the detent holder 16 and are designed to move into and out of engagement with a recess 11a formed along the internal wall of valve housing 11. The triggering mechanism 33 also includes a downwardly tapered annular shoulder section 33b formed along its outer surface which is employed to urge the detent balls 34 radially outwardly when the member 33 is moved axially downwardly. A helical spring 330 encircles operator segment 23d and is restrained at its upper end by engagement with the shoulder extending inwardly from detent holder 16 and at its lower end, by engagement with a shoulder extending radially inwardly from the base of triggering component 33. Axially extending bores 33a formed in the component 33 prevent pressure differentials from developing across the member which would impede its movement. As may be seen by reference to FIG. 5, the shoulder 23e provides a lower limit to travel of the component 33 over the operator 23.

The opening and closing movements of the valve stem 15 through the housing 11 are provided by bellows and spring drives contained within the control housing 13. The bellows portion of the control C includes a lower bellows section 35 and an upper bellows section 36 which enclose lower and upper bellows areas B-1 and B-2 respectively. The areas B-1 and B-2 are completely filled with a non-compressible fluid such as a light weight oil to provide bellows protection in a manner to be described. The lower bellows section 35 is housed within a lower housing portion 13a and the upper section 36 is housed in an upper control housing portion 13b. The upper and lower housing portions are threadedly secured to a central housing member 13c. An alignment sleeve 37 is threadedly engaged to the central housing section and the lower end of the sleeve includes a tubular body 37a which extends downwardly internally of the lower bellows area B-l. The lowermost end of bellows section 35 is secured to an end structure 38 which includes a upwardly directed sleeve 39 telescopically received within the alignment sleeve body 37a. A plurality of radial bores 37a and 38a extend through the components 37a and 38, respectively, to ensure complete filling of the internal areas of the bellows with the non-compressible fluid. A cap 40 is threadedly engaged with the lower end of end structure 38 to provide a filling opening through which the bellows areas may be filled with liquid. The bellows sections are joined to their end structures by a suitable leakproof means such as soldering or welding or otherwise and resilient annular O-ring seals are positioned between threadedly engaged components to provide a leakproof seal of the area confined within the bellows.

The central portion of alignment sleeve 37 includes a restricted opening 41 which functions as a damping orifice to restrict the flow of liquid which in turn prevents short duration, transient pressure changes from operating the valve or causing damage to the control mechanism.

An axially movable safety valving sleeve 42 is mounted for axial movement within the fluid contained in the areas 8-] and B-2. The member 42 includes an annular resilient seal member 43 which is designed to be moved axially between a lower seating surface 44 formed along the upper axial end of alignment sleeve 37 and an upper seating surface 45 formed along an inwardly directed shoulder extending from the housing section 130. A coil spring 46 mounted between the seal sleeve 42 and the alignment sleeve 37 biases the sleeve 42 and seal 43 into engagement with the upper seating surface 45. The sleeve 42 includes an upwardly extending tubular support section 47 which is surrounded by a teflon sleeve 48. The sleeve 48 acts as a smooth underlying surface against which the bellows section 36 may slide. Radial openings 47a extend through the sleeve 47 to ensure complete liquid filling of the area B-2. The upper end of sleeve 47 is threadedly engaged to an end member 49 which holds the sleeve 48 in place and also functions as a bearing member.

The top of bellows 36 is secured to an axially movable upper end assembly 50. A depending sleeve 51 threadedly engaged to the lower end of the assembly extends over a portion of the bellows 36 and terminates in a radially projecting shoulder 510. A spring 52 is mounted between shoulder 51a and the upper surface of the internal shoulder formed on the housing section 130 and functions to close the valve in the event of bellows failure. The upper end of end assembly 50 is threadedly engaged to a bushing 53 which provides an upper restraining shoulder for a resetting spring 54. The lower end of spring 54 is mounted against an inwardly extending shoulder 17a formed on the recocking sleeve 17. A closure spring 55 is mounted about sleeve 51 between relatively movable shoulders 17b and 51a. Radial openings 17b extending through the sleeve 17 prevents a pressure differential from developing across the walls of the sleeve. Casing pressure is communicated into the control C through openings in a protective screen 11b which cover pressure communication ports 56. The ports 56 extend through the valving housing walls and communicate with a bellows control area B-3 formed between the bellows housing 13 and the outer surface of bellows section 36.

The lowermost end of housing 13 is equipped with a removable cap 57 which protects a conventional gas valve 58. The valve 58 employed to inject a gas into a pressure dome B-4 formed between the housing section and the external surface of bellows section 35.

In the operation of the assembly 10, the pressure of the gas in pressure dome B-4 determines the pressure at which the valve will open and close. Under normal operating conditions where gas is being injected into the formation or is being extracted from the formation, the differential between the pressure in dome B-4 and control area B-3 is insufficient to move the valve to closed position and the closure components of the valve are as illustrated in FIG. 4. Stated differently, thepressure in the well conduit and in area 8-3, is greater than that in the dome area B-4 causing the bellows section 36 to contract and the section 35 to elongate or ex pand which in turns holds the valve stem 14 at its lower position. In this position, the seal 18 and seat surface 19a are out of the flow path of the gas moving through the valve V. The pressure in control area B3 is the same as that existing in the well casing below the seal S. When the casing pressure drops below the dome pressure, corresponding to failure of the casing or wellhead structure, the pressure in the area B-3 falls. The decrease in pressure permits the gas charge in the dome B4 to foreshorten the bellows section 35 as illustrated in FIG. 6. This movement of bellows section 35 causes bellows section 36 to elongate. The end assembly 50 is moved upwardly by elongation of bellows section 36 causing the bushing 53 to engage the base of trigger mechanism 33 and push it upwardly against the force of spring 33c. Raising of the triggering mechanism 33 permits detent balls 34 to retract radially out of recess 11a which releases the valve stem 13 from the valve housing 11. During the initial portion of the upward out of the recess 11a, the compressed force of spring 55 is suddenly released to swiftly move the valve stem 14 upwardly through the surrounding housing 11 to provide a snap action closure. Immediately preceding closure, the bellows 35 is compressed as illustrated in FIG. 3. The initial upward movement of the assembly 50 also compresses spring 330. When the detent balls 34 are in their radially retracted position where they are held by engagement with the internal walls of the valve housing 11, the engagement between taper surface 33b and the balls 34 retains the spring 330 in compressed condition.

After damage to the well structure has been repaired, the valve may be reopened by pressuring up from the wellhead or by lowering a suitable mechanism down through the casing to depress the valve stem. During the downward movement of the stem 14 as the valve is being reopened, the spring 33c remains compressed until the detent balls are aligned with detent recess 11a. At this point, the balls are free to move radially outwardly and the compressed force of spring 330 acts against the tapered surface 33d to push the balls outwardly into locking engagement with the recess 11a so that the valve assumes the position illustrated in FIG. 4. The resetting spring 54 is compressed during the return movement of the bellows 35 caused by the pressure increase in the well following valve closure. The force of the compressed spring is released-to snap'the stem 14 fully open during the resetting operation so that the valve closure surfaces are completely withdrawn from the valve flow passage.

An important feature of the present invention is the provision of the safety closure spring 52 which assures closure of the valve in the event of bellows failure. When the valve is in open position, the spring 52 remains in compression. Loss of pressure sealing in the bellows area releases the force of spring 52 which trips the valve into closed position. Thus, when the bellows sections or the dome are ruptured or otherwise begin to leak; the well pressure in area B-3 is communicated into the bellows areas and the dome. When this occurs, the bellows section 36 is permitted to expand with the assistance of the spring 52. The expansion tripsthe triggering mechanism 33.and causes the valve to close.

FIG. 5 of the drawings illustrates a latching mechanism L which includes resilient collet members L-l having inwardly tapered lower end surfaces L-2. If for any reason the valve closure members should fail to automatically close, the latching mechanism L may be lowered through the well casing until the lower, tapered surfaces L-2 of collect fingers L.-l hit and slide over the upper, tapered surfaces 23a of the operator 23 causing the collets to spread outwardly and latch about the operator shoulder 23b. A subsequent upward force exerted through the latching mechanism L causes the valve stem 14 to be moved upwardly which closes the valve by seating the primary seal 18 against the seat 19a.

Because the bellows sections 35 and 36 may be exposed to extremely high pressure differentials, the control C is provided with a means for preventing over contraction or over expansion of the bellows sections which would permanently distort the bellows and thereby them for their intended usage. This safety provision is provided by the safety valving sleeve 42. When the valve is open as illustrated in FIG. 4, the spring 46 is compressed and the sleeve 42 is held at its lowermost axial position by the end assembly 50. In this position, the seal 43 engages the lower seating surface 44 and pressure existing in the bellows area B-2 is isolated from that existing in the bellows area 8-1 to prevent over extension of the bellows 35. Since the upper section 8-2 is filled with an incompressible fluid, extremely high pressures may be tolerated without damage to the bellows sections. In the absence of the protected seal provided by sleeve 42 and seal 43, high pressures in the upper bellows area 8-2 will be communicated to the bellows area B-l causing the lower bellows to over expand outwardly and the upper bellows to over contract inwardly. In the opposite situation, where the pressure in control area B-3 falls below a predetermined value, the valve sleeve 42 is automatically moved upwardly under the influence of the spring 46 causing the seal 43 to seat against the upper seating surface 45. The incompressible fluid filling bellows area B-l prevents the dome charge from overcompressing the bellows 35 and the seal 43 prevents communication of the high pressures existing in bellows area 8-1 to bellows area B-2 which thereby protects bellows 36 from over extension outwardly. The bellows section 36 however remains free to expand and contract within the limits required for proper operation of the valve. By this means, relatively high pressures may be employed in the pressure dome B-4 without damage to the bellows components.

While the valve assembly 10 has been described with reference primarily to its use as an automatic safety valve for use in the event of damage to the well casing or wellhead structure, it may be appreciated that the valve may function as a check valve through which gas may be injected into the well but through which gas is prevented from flowing out of the well. Operation of this type may be effected by establishing a gas charge in dome chamber B-4 which maintains the valve in closed position under normal operating conditions where gas is neither being injected into nor extracted from the formation. Thus, gas pressure in dome 3-4 is low enough to permit the valve to open under the influence of a high gas pressure exerted from the wellhead during gas injection which biases the valve stem into open position.

From the foregoing, it will be appreciated that the assembly of the present invention provides a means whereby maximum producing rates may be acheived by minimizing pressure losses since production may be effected through the well casing. Moreover, by employing a retrievable packer which may be operated on a wireline, the assembly may be quickly and easily replaced or repaired and the valve may be quickly positioned at any desired subsurface location. The bellows protection permits the control to function well even where high pressures are encountered and the snap ac tion closure and opening ensures proper operation of the valve. The foregoing disclosures and description of the invention is illustrative and explanatory thereof, and various changes in the size, shape and materials as well as in the details of the illustrated construction may be made within the scope of the appended claims without departing from the spirit of the invention.

I claim:

1. An automatic safety valve for use in a well conduit comprising:

a. valve body means having flow passage means extending through at least a portion of said valve body means, said passage means including inlet and outlet means;

b. movable valve closure means connected with said valve body meansand movable between opened and closed positions for opening or closing said flow passage means to respectively permit or terminate the flow offluids through said passage means;

c. pressure responsive control means connected with said closure means by a linking means for automatically moving said closure means into said closed position in response to the presence of predetermined pressure conditions within said well conduit;

(1. trigger means cooperating with said control means and said closure means for retaining said closure means in substantially fully opened position, said trigger means further including means for releasing said closure means for movement toward said closed position only when said linking means is moved more than a predetermined amount;

e. powering means included in said closure means and controlled by said trigger means for snapping said closure means toward said closed position when said linking means moves beyond said predetermined amount;

f. a closure portion included in said closure means movable to said closed position for forming a sealing engagement with said flow passage means to terminate flow through said passage means; and

g. releasable locking means included in said trigger means for holding said closure portion in a fully opened position until said control means moves beyond said predetermined amount, movement of said closure means toward said closed position being independent of control means movement following release of said closure means for movement toward said closed position.

2. An automatic safety valve as defined in claim 1 further including surface operable anchoring and sealing means for respectively'anchoring said valve body at a subsurface location within a well conduit and for forming a seal between said well conduit and said valve body means to prevent fluids in said well conduit from flowing axially past said sealing means without first flowing through said passage means whereby closure of said closure means may terminate flow of fluids through said well conduit.

3. An automatic safety valve as defined in claim 1 wherein said valve includes pressure bypass means operable when opened to equalize pressure at the inlet and outlet ends of said passage means when said closure means is in closed position.

4. An automatic safety valve as defined in claim 1 wherein said anchoring and sealing includes a retrievable packer means with radially expansible and retractable securing means, a radially expansible and retractable elastomeric seal and a flow opening extending radially through a supporting packer body.

5. An atuomatic saftey valve as defined in claim 1 wherein:

a. said powering means includes a compressed spring means; and

b. said locking means includes axially movable sleeve means and radially moving ball means.

6. An automatic safety valve as defined in claim 5 whereini a. said control means includes bellows means separating pressure dome means from the well fluid,

said bellows means being movable in response to a pressure differential between the fluid in said dome means and the fluid in said well conduit; and

b. said linking means is operatively connected to said bellows means and movable by said bellows means to release said triggering means when said bellows means moves beyond a predetermined amount.

7. An automatic safety valve as defined in claim 1 further including means operatively connected with said linking means for permitting said control means to move in the direction opposite to that for closing said passage means without unseating said sealing and seat means.

8. An automatic safety valve as defined in claim 7 wherein said control means includes pressure charged bellows means.

9. An automatic safety valve for use in a well conduit comprising:

a. valve body means having a flow passage means extending through at least a portion of said valve body means, said passage means including inlet and outlet means;

b. movable valve closure means connected with said valve body means for opening or closing said passage means to respectively permit or terminate the flow of fluids through said passage means;

c. pressure responsive means connected by a linking means with said closure means, said pressure responsive means being movable from a first position to a second position for automatically moving said closure means from open position into closed position in response to pressure conditions present within said well conduit;

d. valve seat means included in said closure means;

e. valve stem means included in said closure means,

said stem means including sealing means for sealingly engaging and disengaging said seat means to respectively terminate or permit flow through said passage means; and

f. means included in said linking means for permitting said pressure responsive means to return from said second to said first position without unseating said sealing and seat means.

10. An automatic safety valve as defined in claim 9 wherein said valve includes pressure bypass means operable when opened to equalize pressure at the inlet and outlet ends of said passage means when said closure means is in closed position.

11. An automatic safety valve as defined in claim 9 wherein said pressure responsive means includes pressure charged bellows means.

12. An automatic safety valve as defined in claim 9 further including surface operable anchoring and sealing means for respectively anchoring said valve body at a subsurface location within a well conduit and for forming a seal between said well conduit and said valve body means to prevent fluids in said well conduit from flowing axially past said sealing means without first flowing through said passage means whereby closure of said closure means may terminate flow of fluids thorugh said well conduit.

13. An automatic safety valve as defined in claim 12 wherein said anchoring and sealing means includes a retrievable packer means with radially expansible and retractable securing means, a radially expansible and retractable elastomeric seal and a flow opening extending radially through a supporting packer body. 

1. An automatic safety valve for use in a well conduit comprising: a. valve body means having flow passage means extending through at least a portion of said valve body means, said Passage means including inlet and outlet means; b. movable valve closure means connected with said valve body means and movable between opened and closed positions for opening or closing said flow passage means to respectively permit or terminate the flow of fluids through said passage means; c. pressure responsive control means connected with said closure means by a linking means for automatically moving said closure means into said closed position in response to the presence of predetermined pressure conditions within said well conduit; d. trigger means cooperating with said control means and said closure means for retaining said closure means in substantially fully opened position, said trigger means further including means for releasing said closure means for movement toward said closed position only when said linking means is moved more than a predetermined amount; e. powering means included in said closure means and controlled by said trigger means for snapping said closure means toward said closed position when said linking means moves beyond said predetermined amount; f. a closure portion included in said closure means movable to said closed position for forming a sealing engagement with said flow passage means to terminate flow through said passage means; and g. releasable locking means included in said trigger means for holding said closure portion in a fully opened position until said control means moves beyond said predetermined amount, movement of said closure means toward said closed position being independent of control means movement following release of said closure means for movement toward said closed position.
 2. An automatic safety valve as defined in claim 1 further including surface operable anchoring and sealing means for respectively anchoring said valve body at a subsurface location within a well conduit and for forming a seal between said well conduit and said valve body means to prevent fluids in said well conduit from flowing axially past said sealing means without first flowing through said passage means whereby closure of said closure means may terminate flow of fluids through said well conduit.
 3. An automatic safety valve as defined in claim 1 wherein said valve includes pressure bypass means operable when opened to equalize pressure at the inlet and outlet ends of said passage means when said closure means is in closed position.
 4. An automatic safety valve as defined in claim 1 wherein said anchoring and sealing includes a retrievable packer means with radially expansible and retractable securing means, a radially expansible and retractable elastomeric seal and a flow opening extending radially through a supporting packer body.
 5. An atuomatic saftey valve as defined in claim 1 wherein: a. said powering means includes a compressed spring means; and b. said locking means includes axially movable sleeve means and radially moving ball means.
 6. An automatic safety valve as defined in claim 5 wherein: a. said control means includes bellows means separating pressure dome means from the well fluid, said bellows means being movable in response to a pressure differential between the fluid in said dome means and the fluid in said well conduit; and b. said linking means is operatively connected to said bellows means and movable by said bellows means to release said triggering means when said bellows means moves beyond a predetermined amount.
 7. An automatic safety valve as defined in claim 1 further including means operatively connected with said linking means for permitting said control means to move in the direction opposite to that for closing said passage means without unseating said sealing and seat means.
 8. An automatic safety valve as defined in claim 7 wherein said control means includes pressure charged bellows means.
 9. An automatic safety valve for use in a well conduit comprising: a. valve body means having a flow passage means extending through At least a portion of said valve body means, said passage means including inlet and outlet means; b. movable valve closure means connected with said valve body means for opening or closing said passage means to respectively permit or terminate the flow of fluids through said passage means; c. pressure responsive means connected by a linking means with said closure means, said pressure responsive means being movable from a first position to a second position for automatically moving said closure means from open position into closed position in response to pressure conditions present within said well conduit; d. valve seat means included in said closure means; e. valve stem means included in said closure means, said stem means including sealing means for sealingly engaging and disengaging said seat means to respectively terminate or permit flow through said passage means; and f. means included in said linking means for permitting said pressure responsive means to return from said second to said first position without unseating said sealing and seat means.
 10. An automatic safety valve as defined in claim 9 wherein said valve includes pressure bypass means operable when opened to equalize pressure at the inlet and outlet ends of said passage means when said closure means is in closed position.
 11. An automatic safety valve as defined in claim 9 wherein said pressure responsive means includes pressure charged bellows means.
 12. An automatic safety valve as defined in claim 9 further including surface operable anchoring and sealing means for respectively anchoring said valve body at a subsurface location within a well conduit and for forming a seal between said well conduit and said valve body means to prevent fluids in said well conduit from flowing axially past said sealing means without first flowing through said passage means whereby closure of said closure means may terminate flow of fluids thorugh said well conduit.
 13. An automatic safety valve as defined in claim 12 wherein said anchoring and sealing means includes a retrievable packer means with radially expansible and retractable securing means, a radially expansible and retractable elastomeric seal and a flow opening extending radially through a supporting packer body. 